This study aimed to investigate the impact of implementing Open Educational Resources (OER) course materials on student engagement and achievement in a 10th grade English Language Arts (ELA) classroom at a high-poverty, rural school district. Research suggests that the implementation of OER materials in a K-12 setting can positively impact student engagement and achievement without adding a financial burden to rural, high poverty districts. A constructivist theoretical research paradigm with a mixed methods methodology was used to answer the research question: "How does the use of an Open Educational Resources (OER) textbook by a 10th grade ELA teacher impact student engagement and achievement?" The study aimed to provide quantitative and qualitative data about the impact of OER materials on student learning and engagement and help to fill the research gap in K-12 OER implementation. Though quantitative data was not found statistically significant, descriptive statistics and qualitative data suggest that student engagement and achievement was improved through the use of OER materials created by their teacher. [The dissertation citations contained here are published with the permission of ProQuest LLC. Further reproduction is prohibited without permission. Copies of dissertations may be obtained by Telephone (800) 1-800-521-0600. Web page: http://bibliotheek.ehb.be:2222/en-US/products/dissertations/individuals.shtml.]